Maybe you could find a long arm to rent. In my area of the world, there is a sales place that has a long arm machine they rent out by the hour. If you happen to already know how to use one, you can skip the lessons. I haven't done it yet, but I have a friend who rents the machine set up to long arm her bigger quilts, and says it's worth the money.
I quilted a double size quilt on my regular machine last winter by setting up on a card table in the middle of my family room and quilting it. Was a hassle but I was able to do it. My sewing room at the time was not able to accommodate quilting my quilt.